不同生产阶段煤层气产量预测的Weibull模型方法研究

Study of Coalbed Methane Production Forecast at Different Stages by Using Weibull Model

煤层气的开采因其长时间的排水降压过程,产气量的变化规律不同于常规油气产量变化规律。Weibull模型方法可以实现对煤层气产量快速准确的预测,既能预测出产气高峰的时间及产量,又能对递减阶段产量进行预测,但是Weibull模型方法在线性回归求参数时难以获得较好的直线段。针对Weibull模型的曲线特点,对煤层气产量进行分段预测,即分为产量上升段和下降段进行预测。该方法不仅克服了Weibull模型线性回归时直线段难以获得的不足,而且能够较为准确地对不同生产阶段煤层气的产量进行预测。通过对数值模拟结果和实际资料进行拟合发现,该方法操作简便、准确性高,具有一定的实用性和推广价值。

Because of the long-term water displacement of coalbed methane ( CBM ), its production variation rule differed from conventional oil and gas.The Weibull model could make a quick and precise forecast of CBM production both at production rising and declining stages.And it could also give the peak production and its time of occurrence.However , it was difficult to determine straight lines in liner regression with Weibull Model.In allusion to the curve characteristics , the production of CBM was predicted in section , that was the prediction of production rising and declining , This method not only can overcome the shortage in linear regression of Weibull Model , but also can predict the production in different periods.It is found out from numerical simulation and data fitting that it is easy operation and high precision , it is adaptability and worthy to be popularized.